Viscosity Of Liquid Water Research Articles

Analysis of the Temperature Effect on the Liquids Viscosity

This study aims to analyse the effect of temperature on the viscosity of liquid water and cooking oil using the experimental method. Viscosity is a measure of the viscosity of a liquid and can be affected by temperature. In this study, a series of experiments were conducted using water and cooking oil as test materials. The samples were tested for viscosity at different temperatures using a thermometer. Experiments were conducted at several varying temperatures, ranging from room temperature to temperature after heating. The viscosity test results were correlated with temperature and analysed to see the pattern of change. Based on the analysis results, it can be concluded whether the viscosity of water and cooking oil increases or decreases as the temperature increases. In addition, it was found that there is a difference in viscosity response between water and cooking oil to temperature changes. The results of this study show the influence between temperature and viscosity of liquids, especially water and cooking oil. Keywords: cooking oil, liquid, temperature, viscosity, water.

Viscosity in water from first-principles and deep-neural-network simulations

We report on an extensive study of the viscosity of liquid water at near-ambient conditions, performed within the Green-Kubo theory of linear response and equilibrium ab initio molecular dynamics (AIMD), based on density-functional theory (DFT). In order to cope with the long simulation times necessary to achieve an acceptable statistical accuracy, our ab initio approach is enhanced with deep-neural-network potentials (NNP). This approach is first validated against AIMD results, obtained by using the Perdew–Burke–Ernzerhof (PBE) exchange-correlation functional and paying careful attention to crucial, yet often overlooked, aspects of the statistical data analysis. Then, we train a second NNP to a dataset generated from the Strongly Constrained and Appropriately Normed (SCAN) functional. Once the error resulting from the imperfect prediction of the melting line is offset by referring the simulated temperature to the theoretical melting one, our SCAN predictions of the shear viscosity of water are in very good agreement with experiments.

Ice Penetration by a Bluff-Body Melting Probe

Abstract We analyze the operation of melting probes as a Stefan problem for the liquid/solid interface surrounding the probe. We assume that the liquid layer is thin and, therefore, amenable to analysis by the lubrication theory. The resulting Stefan problem is solvable in the closed form. The solution determines the dependence of the penetration speed on the temperature differential between the probe and the surrounding ice, the size, shape and weight of the probe, the viscosity of liquid water and the thermal properties of solid ice.

Why is Ice Slippery? Simulations of Shear Viscosity of the Quasi-Liquid Layer on Ice.

The temperature and depth dependence of the shear viscosity (η) of the quasi-liquid layer (QLL) of water on ice-Ih crystals was determined using simulations of the TIP4P/Ice model. The crystals display either the basal {0001} or prismatic {101̅0} facets, and we find that the QLL viscosity depends on the presented facet, the distance from the solid/liquid interface, and the undercooling temperature. Structural order parameters provide two distinct estimates of the QLL widths, which are found to range from 6.0 to 7.8 Å, and depend on the facet and undercooling temperature. Above 260 K, the viscosity of the vapor-adjacent water layer is significantly less viscous than the solid-adjacent layer and is also lower than the viscosity of liquid water.

Near-surface viscosity effects on capillary rise of water in nanotubes.

In this paper, we present an approach for predicting nanoscale capillary imbibitions using the Lucas-Washburn (LW) theory. Molecular dynamics (MD) simulations were employed to investigate the effects of surface forces on the viscosity of liquid water. This provides an update to the modified LW equation that considered only a nanoscale slip length. An initial water nanodroplet study was performed to properly elucidate the wetting behavior of copper and gold surfaces. Intermolecular interaction strengths between water and corresponding solid surfaces were determined by matching the contact angle values obtained by experimental measurements. The migration of liquid water into copper and gold capillaries was measured by MD simulations and was found to differ from the modified LW equation. We found that the liquid layering in the vicinity of the solid surface induces a higher density and viscosity, leading to a slower MD uptake of fluid into the capillaries than was theoretically predicted. The near-surface viscosity for the nanoscale-confined water was defined and calculated for the thin film of water that was sheared between the two solid surfaces, as the ratio of water shear stress to the applied shear rate. Considering the effects of both the interface viscosity and slip length of the fluid, we successfully predicted the MD-measured fluid rise in the nanotubes.

Energy-conserving dissipative particle dynamics with temperature-dependent properties

The dynamic properties of fluid, including diffusivity and viscosity, are temperature-dependent and can significantly influence the flow dynamics of mesoscopic non-isothermal systems. To capture the correct temperature-dependence of a fluid, an energy-conserving dissipative particle dynamics (eDPD) model is developed by expressing the weighting terms of the dissipative force and the random force as functions of temperature. The diffusivity and viscosity of liquid water at various temperatures ranging from 273 K to 373 K are used as examples for verifying the proposed model. Simulations of a Poiseuille flow and a steady case of heat conduction for reproducing the Fourier law are carried out to validate the present eDPD formulation and the thermal boundary conditions. Results show that the present eDPD model recovers the standard DPD model when isothermal fluid systems are considered. For non-isothermal fluid systems, the present model can predict the diffusivity and viscosity consistent with available experimental data of liquid water at various temperatures. Moreover, an analytical formula for determining the mesoscopic heat friction is proposed. The validity of the formula is confirmed by reproducing the experimental data for Prandtl number of liquid water at various temperatures. The proposed method is demonstrated in water but it can be readily extended to other liquids.

Viscosity Ratio Measurements with Capillary Viscometers

Viscosity ratio measurements made with capillary viscometers exploit the accurate values of the viscosity of helium calculated ab initio. Accurate values of the argon-to-helium viscosity ratio are now used for primary acoustic gas thermometry and for the most accurate redeterminations of the Boltzmann constant. Accurate viscosity ratio measurements enable the calibration of laminar flow meters with surrogate gases and their use with process gases. We review ratio viscometers that comprise one, two, and four capillaries. A single capillary is a ratio viscometer when it is used to measure multiple gases sequentially, while two- and four-capillary viscometers are instruments intended for ratio measurements. We consider gases and Newtonian liquids, with a focus on the two-capillary gas viscometer and its extension to pressures up to 100 MPa. A single-capillary viscometer could measure the ratio (viscosity of liquid water)/(viscosity of gaseous helium) thereby reducing the uncertainty of the liquid viscosity scale relative to the international system of units.

Equilibrium molecular dynamics calculation of the bulk viscosity of liquid water

Twenty independent equilibrium molecular dynamics simulations were performed in NVE ensemble to calculate the bulk viscosity of water at a temperature of 303 K and a density of 0.999 gcm−3. The energy of each simulation with a production time of 200ps was conserved within 1 part in 104. By stopping the velocity-scaling procedure at a proper step, the energies of independent simulations were specified precisely. This caused the simulations of different start configurations to sample the same NVE ensemble. The shear viscosity of SPC/E water obtained in the present study was 6.5±0.4 × 10−4 Pas, which is in close agreement with a previous calculation in the NVT ensemble (Balasubramanian, S., Mundy, C. J., and Klein, M. L., 1996, J. clzern. Phys., 105, 11 190). The bulk viscosity was 15.5 ± 1.6 × 10−4 Pas, which is 27% smaller than the experimental value. Thus, like its behaviour in predicting the shear viscosity, the SPC/E model also underestimates the bulk viscosity of real water.

Viscosity of liquid water from computer simulations with a polarizable potential model

The longitudinal and shear viscosity of water are calculated by molecular dynamics simulation with a polarizable potential model at room temperature. To overcome the difficulty of evaluating directly the stress autocorrelation function of a system with intrinsically many-body forces, we have resorted to the analysis of the wave-vector-dependent longitudinal and transverse-current correlation functions. In a memory function formalism, the generalized viscosity can be evaluated as a function of the wave vector k. By extrapolating to k=0, we find longitudinal and shear viscosity values in better agreement with the experimental value than the corresponding quantities evaluated by making use of a nonpolarizable potential model. This result points out that for a realistic reproduction of transport quantities, it is crucial to take into account many-body contributions to the interaction potential.

A prediction of the abnormal behavior in the viscosity of liquid water under pressure

A phenomenological theory of viscosity proposed by authors was applied to liquid water under high pressure. Thermodynamic properties used in the calculation were obtained by using the theory of liquid proposed by Pak [13]. The calculated viscosities decreased abnormally with increasing pressure. We found this behavior was due to the decrease of the absolute value of kinetic and internal pressure with the pressure increase near 273.15 K.

Viscosity of liquid water in the range −8 °C to 150 °C

The paper re-analyzes the results of earlier, very precise measurements of the viscosity of water at essentially atmospheric pressure. This is done in terms of a new, theoretically-based equation for the operation of a capillary viscometer rather than in terms of semi-empirical equations used by the original authors. The new analysis eliminates possible systematic errors and permits the establishment of realistic error bounds for water in its role as a standard reference substance for viscosity. The latter are smaller than those embodied in the most recent International Formulation. Standard values of the ratio of viscosity at a temperature T to its value at 20 °C have been derived from the re-analyzed data because the uncertainty of this ratio is an order of magnitude smaller than that of the absolute values. The ratios are used to generate absolute values with the aid of the standard NBS datum μ=1002.0 μPa s at 20 °C. The viscosity ratios have been correlated with the aid of two empirical equations. The more accurate equation covers the range 0 °C?t ?40 °C with an uncertainty of ±0.05%. The less accurate equation covers the wider range −8 °C?t?150 °C with the more limited accuracy of ±0.2%. The two empirical equations are compatible with each other to 0.09%.

Viscosity of Liquid Water and Superheated Steam

IN previous articles1,2 we have shown that the equation describes the atmospheric pressure viscosities of many liquids with remarkable accuracy. Equation (1) was obtained from the Cohen and Turnbull relationship between the diffusion coefficient D and “the average free volume per molecule”, Vf, defined by Vf = v−v0, where v is the average volume per molecule in the liquid and v0 the van der Waals volume of the molecule3.

Viscosity of liquid water from 25 to 150.degree. measurements in pressurized glass capillary viscometer

Viscosity of liquid water from 25 to 150.degree. measurements in pressurized glass capillary viscometer

``Free Volume'' and the Viscosity of Liquid Water

The viscosity of liquid water between −10° and +150°C (Psat=4.7 atm) is expressed by the equation: η=A exp[B/ (T−T0)], in which A = 290 μp, B = 510°, and T0 = 150°K. The true temperature-independent activation energy for viscous flow is E = RB = 1020 cal/mole. The ``free volume'' representation uses the equation η=A exp(1/f), in which the free-volume fraction, f=vf/vl, increases linearly with temperature above the theoretical zero point, T0. Thus, f=(T−T0)/B. It evolves that f coincides with the volume fraction of unbonded water molecules, as defined by a structural model reported recently by Némethy and Scheraga. This empirical correlation between the viscosity and the structure of liquid water demonstrates the effects of internal structural rearrangements, which are not directly reflected in changes in the total volume. The implications regarding the effects of temperature and pressure on viscosity and other relaxation processes, particularly in hydrogen-bonded, structured liquids, are discussed.